Senior Thermal Engineer

The Role

You will design and iterate on heat exchangers, translating OEM specifications into novel concepts and turning them into simulation-backed designs and validated hardware. This role rewards engineers who are excited by invention: developing new architectures, challenging defaults, and making principled trade-offs when reality disagrees with a model. You'll work closely with product leads and OEM manufacturing partners, using Phasic's AI-driven design process to explore the design space quickly and intelligently. In the first 6 to 12 months, success means creating new HX solutions (and improving existing ones) that hit aggressive thermal and pressure-drop targets and hold up in real-world testing and certification.

What You'll Do

• Translate OEM specifications into heat exchanger concepts and detailed geometries, then iterate quickly toward performance and manufacturability targets.
• Use both 1D/first-principles models and high-fidelity 3D CFD simulation to make design decisions (not just generate reports) and communicate trade-offs clearly.
• Leverage Phasic's AI-driven design process to explore the design space, generate candidates, and converge on novel solutions.
• Design with additive manufacturing constraints in mind (powder removal, support strategy, distortion, post-processing), and partner closely with manufacturing to ensure concepts can become reliable hardware.
• Work with OEM manufacturing partners and internal product leads to align on requirements, constraints, and the "definition of done" for each design.
• Close the loop between simulation and physical testing by planning validation, interpreting results, and improving models/design rules when they diverge.
• Build reusable tools and artifacts (simulation setups, parameterized studies, design guidelines, validation datasets) that increase the team's speed and quality over time.

What You Bring: Required

• Masters or greater in Mechanical Engineering, Thermal Engineering, or a related field with a concentration in thermal-fluid sciences (waste heat recovery or similar backgrounds are a plus).
• 5+ years of hands-on experience designing heat exchangers, cold plates, or thermal management hardware; not just analyzing other people's designs, but creating and iterating on geometry and standing behind performance outcomes.
• Experience building first-principles 1D heat-exchanger models (MATLAB, EES, or Python) to support early-stage thermal design and performance assessment.
• Demonstrated proficiency in CFD and thermal simulation/optimization tools (STAR-CCM+, Ansys Fluent, COMSOL, OpenFOAM or equivalent); you should be able to set up conjugate heat transfer problems for single phase and two phase flow regimes and have excellent understanding of CFD solvers. Integrating optimization with CFD workflows is essential.
• Working knowledge of at least one CAD environment (SolidWorks, Siemens NX, or similar) and comfort designing internal flow passages and complex 3D geometries. Proficiency in surface modelling is a plus.
• Experience with physical thermal testing, including instrumenting experiments, collecting data, and using the results to validate or challenge simulation outputs. This should include basic instrument calibration and uncertainty/error analysis. Experience using test data to calibrate CFD models is essential.
• Clear, direct communication; you can explain a thermal trade-off to a non-thermal engineer and hold your ground when the data supports it.
• Ability to make progress in ambiguous environments by rapidly defining assumptions, proposing initial solutions, and iterating based on feedback or new data.

What You Bring: Nice to Have

• Experience with metal additive manufacturing (L-PBF, SLM, DED, or binder jetting), especially designing parts that account for AM-specific constraints.
• Familiarity with data center liquid cooling systems, CDUs, or rack-level thermal architectures.
• Experience with topology optimization or generative design tools applied to thermal problems.
• Experience working with contract manufacturers and navigating the gap between design intent and as-built reality.
• Background in a startup or small-team environment where you wore multiple hats and shipped hardware under time pressure.

Why Phasic

• Join as a single-digit hire at a seed-stage company and own real outcomes from day one.
• Get meaningful early-stage equity and the chance to build value over years, not quarters.
• Work on a hard, high-leverage problem at the intersection of physics, manufacturing, and AI infrastructure.
• Be part of a team that values craft, speed with rigor, and straightforward feedback, and celebrates excellent execution.

Compensation and Benefits

The base salary range for this role is $175,000 - $225,000 USD, depending on experience and qualifications. Actual compensation will be determined based on a variety of factors including skills, experience, and location.

In addition to base salary, this role includes meaningful early-stage equity. As a seed-stage company, our benefits are built for where we are and designed to grow as we do. Today that includes healthcare coverage, paid time off, and a team that genuinely values flexibility and work-life balance.

Equal Opportunity

Phasic Energy is an equal opportunity employer. We evaluate qualified applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, veteran status, genetic information, or any other characteristic protected by applicable law. We are committed to building a diverse and inclusive team.

If you require a reasonable accommodation during the application or interview process, please contact us at careers@phasic.ai.